1. Field of the Invention
The present invention relates to a method of manufacturing an electron source and an image-forming apparatus, and an apparatus for manufacturing the same.
2. Related Background Art
Two kinds of device, i.e., a thermoionic cathode and a cold cathode are conventionally known as an electron-emitting device. Known cold cathode include a field emitter device (hereinafter referred to as xe2x80x9cFE typexe2x80x9d), a metal/insulating layer/metal type emitting device (hereinafter referred to as xe2x80x9cMIM typexe2x80x9d), and a surface conduction electron-emitting device.
Known examples of the FE type are disclosed, for example, by W. P. Dyke and W. W. Dolan, in xe2x80x9cField emissionxe2x80x9d, Advance in Electron Physics, 8, 89 (1956) or in C. A. Spindt, xe2x80x9cPhysical properties of thin-film field emission cathodes with molybdenium conesxe2x80x9d, J. Appl. Phys. 47, 5248 (1976).
Known examples of the MIM type are disclosed, by C. A. Mead, in xe2x80x9cOperation of tunnel-emission Devicesxe2x80x9d, J. Appl. Phys., 32, 646 (1961), for example.
A surface conduction electron-emitting device disclosed in, for example, M. I. Elinson, Radio Eng. Electron Phys., 10, 1290 (1965) or others as will be described later are known.
A surface conduction electron-emitting device utilizes the phenomenon in which electron emission is caused by flowing an electric current to a thin film formed with a small area on a substrate and in parallel to the film surface. This surface conduction electron-emitting device that has been reported includes those employing a SnO2 thin film developed by Elinson et al. named in the above, those employing an Au thin film (G. Dittmer, xe2x80x9cThin Solid Filmsxe2x80x9d, Vol.9, p.317, 1972), those employing a In203/SnO2 thin film (M. Hartwell and C. G. Fonstad, xe2x80x9cIEEE Trans. ED Conf.xe2x80x9d, p.519, 1975), and those employing a carbon thin film (Hisashi Araki, et al. xe2x80x9cSHINKU(Vacuum)xe2x80x9d, Vol.26, No.1, p.22, 1983).
Typical device structure example of these surface conduction electron-emitting devices is shown in FIG. 35, which is a plan view of a device disclosed by M. Hartwell et al. named in the above. In this figure, reference numeral 3001 denotes a substrate, and reference numeral 3004 denotes an electroconductive thin film made of metal oxides formed by sputtering. The electroconductive thin film 3004 is formed into an H-shaped plan configuration as illustrated. The electroconductive thin film 3004 is subjected to an energization operation called an energization forming, as will be described later, to form an electron-emitting region 3005. In FIG. 35, intervals L and W are defined as 0.5 to 1 mm and 0.1 mm, respectively. For convenience of illustration, the electron-emitting region 3005 is shown as a rectangle formed in the middle of the electroconductive thin film 3004, but it is schematically shown, and the exact position or configuration of the actual electron-emitting region is not faithfully expressed herein.
In the above-stated surface conduction electron-emitting device representative of those disclosed in M. Hartwell et al., it has been typically practiced to form the electron-emitting region 3005 by an energization operation called an energization forming on the electroconductive thin film 3004 before effecting the electron emission. More specifically, in an energization forming, a constant dc voltage or dc voltage with an increase at a greatly slow rate, for example, on the order of 1 v/minute is applied to the both ends of the electroconductive thin film 3004, and a current is made to flow to the electroconductive thin film to bring the electroconductive thin film 3004 to be locally destroyed, deformed or denatured, thus forming the electron-emitting region 3005 kept in a state of electrically high resistance. A gap is formed in a portion of the electroconductive thin film 3004 which is brought to be locally destroyed, deformed or denatured. If an appropriate voltage is applied to the electroconductive thin film 3004 after the energization forming, an electron emission is generated in the vicinity of the gap.
The foregoing surface conduction electron-emitting device has an advantage to form a number of devices over a large area since it is simple in structure and is easily manufactured. Therefore, methods of arranging and driving a number of devices have been studied as disclosed by the present applicant in Japanese Patent Application Laid-Open No. 64-31332.
An application of surface conduction electron-emitting devices which has been studied includes an image-forming apparatus such as an image display device or an image recording device, and a charging beam source.
In particular, an application to the image display device which has been studied includes an image display device taking advantage of a combination of a surface conduction electron-emitting device and a phosphor irradiated by an electron to effect light-emission, as disclosed by the present applicant in U.S. Pat. No. 5,066,883 and in Japanese Patent Application Laid-Open No. 2-257551. The image display device with use of a combination of a surface conduction electron-emitting device and a phosphor is expected to be more excellent in nature than other types of image display device in the prior art. It can be excellent in no requirement for back light since it is of a self-emission type or in larger view angle, as compared to a recently popular liquid crystal display device, for example.
An object of the present invention is to provide a method of manufacturing an electron source and an imageforming apparatus, and an apparatus for manufacturing the same, in which occurrence of an abnormal voltage can be suppressed in energization processes used for a manufacture process of an electron source.
The present invention provides a method of manufacturing an electron source comprising an electron-emitting device comprising a pair of electroconductive members, and first wires and second wires being connected to the pair of electroconductive members, respectively, the method comprising the step of applying a pulse voltage to the pair of electroconductive members via the first and/or second wires, wherein the pulse voltage is a pulse where a specific frequency band included in a pulse voltage outputted from a pulse power supply is restricted.
Further, according to the present invention, the frequency band is varied according to impedance fluctuation of the electron source.
The present invention also provides a method of manufacturing an electron source comprising an electron-emitting device comprising a pair of electroconductive members, and first wires and second wires being connected to the pair of electroconductive members, respectively, the method comprising the step of applying a pulse voltage between the pair of electroconductive members via the first and/or second wires so that a voltage increases and/or decreases in steps, wherein the pulse voltage increases by at least two steps from its absolute minimum voltage Vmin to its absolute maximum voltage Vmax, and wherein the absolute maximum value of a voltage to be effectively applied to the pair of electroconductive members is not larger than Vmax+|Vmaxxe2x88x92Vmin|xc3x970.1.
Further, according to the present invention, the maximum value of a voltage to be effectively applied to the pair of electroconductive members is not larger than Vmax+|Vmaxxe2x88x92Vmin|xc3x970.05.
Still further, according to the present invention, wherein the maximum value of a voltage to be effectively applied to the pair of electroconductive members is not larger than Vmax+|Vmaxxe2x88x92Vmin|xc3x970.01.
Still further, according to the present invention, the voltage applying step is a step to form a gap on an electroconductive film connecting the pair of electroconductive members.
Still further, according to the present invention, the voltage applying step is a step to arrange a carbon film between the pair of electroconductive members.
The present invention also applies the foregoing manufacture method of an electron source to a manufacture method of an electron source which is used for an image-forming apparatus.
The present invention also provides an apparatus for manufacturing an electron source comprising an electron-emitting device comprising a pair of electroconductive members, and first wires and second wires being connected to the pair of electroconductive members, respectively, the apparatus comprising: a pulse voltage source for applying a pulse voltage to the pair of electroconductive members via the first and/or second wires; and a pulse voltage control circuit connecting the pulse voltage source and the first and/or second wires, wherein the pulse voltage control circuit restricts a specific frequency band included in the pulse voltage.
Further, according to the present invention, the voltage control circuit makes the frequency band to be restricted vary according to impedance fluctuation of the electron source.
Still further, according to the present invention, the voltage control circuit includes a low-pass filter circuit.
Still further, according to the present invention, the voltage control circuit is provided with a capacitance component and a resistance component.
The present invention also applies the foregoing manufacture apparatus for an electron source to an apparatus for manufacturing an electron source which is used for an image-forming apparatus.